DESCRIPTION: (Applicant's Abstract) The pharmacologic basis of smoking has received a lot of attention with development of nicotine replacement for smoking cessation. Long-term abstinence achieved by nicotine replacement has been modest, suggesting that smoking involves non-nicotinic factors. The behavior of smoking is subject to conditioning processes and comes under the control of external and internal stimuli that serve as cues for smoking. The main objective of this project is to expand our knowledge of the cues associated with smoking in everyday settings. Data on these associations will be provided by smokers using a diary to monitor their location, activity, moods, and social setting during two work and two nonwork days at times they smoke and at control non-smoking occasions. In addition, subjects will wear devices that record heart rate and physical activity continuously during each day to determine how these measures are associated with smoking. In a second set of four days of recording, subjects will wear either a nicotine or a placebo patch to determine how associations between smoking and the diary and physiological measures are affected by added nicotine. We will also determine the role of smoking rate, gender, nicotine dependence, personality and other characteristics in the above relationships. The specific aims are: 1. To evaluate the stimulus control of smoking in everyday situations using ambulatory methods. 2. To determine whether stimulus control differs as a function of smoking rate, gender, and individual differences in nicotine dependence, hostility, and other characteristics. 3. To evaluate the consistency of stimulus control of smoking from day to day and as a function of social context (work, nonwork days). 4. To evaluate the effects of added nicotine administered by patch compared to a placebo on the stimulus control of smoking and the relation of these effects to gender, smoking rate, and nicotine dependence. 5. To explore the role of heart rate and physical activity level in association with smoking. 6. To explore the role of personality traits (hostility, anxiety, depression) and other characteristics in the above rdationships. Participants in the study will be 60 men and 60 women heavy and moderate smokers. This research should add to our knowledge of non-nicotinic factors in smoking and help in the design of more effective smoking cessation programs.